It is highly unlikely that there is any invention that has remained completely unchanged and never undergone any modifications or improvements. Throughout history, innovations and inventions have continuously evolved and improved as new knowledge, technologies, and materials become available.
Even iconic and enduring inventions that have had a significant impact on society, such as the wheel, the printing press, or the light bulb, have undergone numerous modifications and refinements over time. These changes have been driven by the desire to enhance efficiency, reliability, safety, or to adapt to changing needs and advancements in related fields.
While there may be examples of inventions that have remained relatively unchanged for long periods, it is rare for them to have never undergone any modifications at all. The iterative process of innovation and improvement is inherent to the nature of human progress, and the pursuit of better solutions is a fundamental aspect of scientific and technological advancement.